The treatment of certain diseases often requires infusion of drugs or medicants into the body. When infusing such medicants, a caregiver will often make a venipuncture with a cannula to access a vein, and thread a catheter through the vein to a desired location. The catheter includes a distal end, a proximal end and one or more lumens therebetween. The distal end of the catheter may be placed at a variety of locations including the superior vena cava. The proximal end of the catheter is then coupled to a portal within the body or passes exterior of the body.
Generally, portals are sealed reservoirs accessible through a septum. The portal is connected to the proximal end of the catheter and subcutaneously implanted within the patient. Catheters which pass external of the body include: PICC (Peripherally Inserted Central Catheter) catheters, which access the superior vena cave through the cephalic vein in the arm; and chest catheters (often referred to as Hickman catheters) which pass through a tunnel bored into the chest then into the cephalic vein.
The prior art provides for methods and devices to locate the distal end of the catheter within the body as the catheter is inserted into the vein. For example, commonly assigned U.S. Pat. No. 4,905,698 to Strohl et al describes a method and apparatus for catheter location determination. The method and apparatus of Strohl utilizes a source which generates an alternating magnetic field, and a detector positioned proximate the distal end of the catheter. The detector generates a voltage in response to the proximity of the field generated by the source. The phase of the voltage in the detector shifts as the source passes over it. By referencing anatomical landmarks at the time the phase shift occurs, the caregiver can determine the exact location of the detector, and thus the location of the tip of the catheter.
The method and apparatus of Strohl are advantageous because the tip of the catheter can be located without use of fluoroscopy. Fluoroscopy involves using x-rays to locate the distal end of the catheter.
After the catheter is implanted, medicants are delivered therethrough to the desired location. Medicants are introduced either directly into the catheter, as in the case of a PICC catheter or chest catheter, or through bolus injection or continuous infusion into the portal. Each technique for delivering medicants has associated advantages which a caregiver evaluates in determining how medicants will be delivered to a patient.
In the prior art, catheters are sold in predetermined lengths. Often, the length of the catheter purchased does not meet the exact needs of the patient. In the case of catheters used in conjunction with portals, the caregiver positions the distal end of the catheter within the patient, for example at the superior vena cava, and trims the proximal end so that the catheter is the proper length This is especially necessary when the length of the catheter is greater than the distance between the superior vena cava and the location of the portal. The distal end will be located, and the proximal end will be trimmed prior to connection with the portal.
If the device of Strohl has been used to locate the distal end of the catheter, in connection with placement of a portal, the caregiver will remove the device of Strohl prior to trimming the proximal end of the catheter. The device of Strohl is removed by disconnecting a coupling positioned on an associated junction box. The caregiver then trims the proximal end of the catheter, fits the portal to the proximal end of the catheter and places the portal within the patient.
Chest type and PICC catheters are also sold in predetermined lengths which do not often meet the needs of the patient. To place a chest or PICC catheter the caregiver would lay the catheter over the patient to determine the proper length and trim the distal end. The catheter would then be placed using fluoroscopy.
In the prior art, use of devices of the type described in Strohl U.S. Pat. No. 4,905,698 are not used with either chest or PICC type catheters. Use of these devices in the prior art are limited to use with portals. In particular, the device of Strohl is secured within the lumen of the catheter so that the detector of Strohl is positioned at the distal end of the catheter. When the distal end of the catheter has been located the proximal end is trimmed. Both PICC and chest catheters include permanent fittings on their proximal ends which cannot be trimmed. The device and method taught by Strohl cannot be used with catheters which include fittings at the proximal end, such as PICC catheters or chest catheters, because the proximal end of the catheter cannot be trimmed. Therefore, a need has arisen to provide an apparatus and method which permits the safe and convenient use of the device of Strohl or other related devices with PICC and chest catheters.